function Load_DLL(DllName: PChar; PID: dword): boolean;
//DllName - имя библиотеки, PID - id блокнота
var
hProc: dword;
lpStartAddress, pmem: pointer;
wrb, lpThId: dword;
begin
if not FileExists(DLLName) then
 ShowMessage('dll not found')
else
 begin
  hProc:=OpenProcess(PROCESS_ALL_ACCESS or PROCESS_VM_WRITE, true, PID);
  if (hProc<>0) then
   begin
    lpStartAddress:= GetProcAddress(GetModuleHandle('kernel32.dll'), 'LoadLibraryA');
    pmem:= VirtualAllocEx(hProc, nil, 255, MEM_COMMIT, PAGE_READWRITE);
    if (pmem=nil) then
     result:=false
    else
     begin
      if not WriteProcessMemory(hProc, pmem, DllName, Length(DllName), wrb) then
       result:=false
      else
       if (dword(Length(DllName)) = wrb) then
        result:=CreateRemoteThread(hProc, nil, 0, lpStartAddress, pmem, 0, lpThId)<>0
       else
        result:=false;
     end;
   end
  else
   result:=false;
 end;
end;

library ShowMe;

uses
 Windows, Dialogs;

begin
try
 ShowMessage('dll is load');
except
end;
end.

lpStartAddress:= GetProcAddress(GetModuleHandle('kernel32.dll'), 'LoadLibraryW');

program rp;

uses
 Windows,
 Tlhelp32,
 SysUtils,
 Dialogs;

function Load_DLL(DllName: PChar; PID: dword): boolean;
var
hProc: dword;
lpStartAddress, pmem: pointer;
wrb, lpThId: dword;
begin
if not FileExists(DLLName) then
 ShowMessage('dll not found')
else
 begin
  hProc:=OpenProcess(PROCESS_ALL_ACCESS or PROCESS_VM_WRITE, true, PID);
  if (hProc<>0) then
   begin
    lpStartAddress:= GetProcAddress(GetModuleHandle('kernel32.dll'), 'LoadLibraryW');
    pmem:= VirtualAllocEx(hProc, nil, 255, MEM_COMMIT, PAGE_READWRITE);
    if (pmem=nil) then
     result:=false
    else
     begin
      if not WriteProcessMemory(hProc, pmem, DllName, Length(DllName), wrb) then
       result:=false
      else
       if (dword(Length(DllName)) = wrb) then
        result:=CreateRemoteThread(hProc, nil, 0, lpStartAddress, pmem, 0, lpThId)<>0
       else
        result:=false;
     end;
   end
  else
   result:=false;
 end;
end;

function SetSeDebugPrivilege:boolean;
var
ht:THandle;
luid:TLargeInteger;
tkp:TTokenPrivileges;
rl:Cardinal;
begin
if OpenProcessToken(GetCurrentProcess, TOKEN_ADJUST_PRIVILEGES, ht) then
 begin
  LookupPrivilegeValue(nil, 'SeDebugPrivilege', luid);
  tkp.Privileges[0].Luid:=luid;
  tkp.PrivilegeCount:=1;
  tkp.Privileges[0].Attributes:=SE_PRIVILEGE_ENABLED;
  if AdjustTokenPrivileges(ht, false, tkp, 0, nil, rl) then
   result:=true
  else
   result:=false;
 end
else
 result:=false;
end;

function GetPID(ExeFileName: string): dword;
var
ContinueLoop, ffound: boolean;
FSnapshotHandle: THandle;
FProcessEntry32: TProcessEntry32;
UpEFN: string;
begin
result:=0;
ffound:=false;
UpEFN:=UpperCase(ExeFileName);
FSnapshotHandle:=CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
FProcessEntry32.dwSize:=Sizeof(FProcessEntry32);
ContinueLoop:=Process32First(FSnapshotHandle, FProcessEntry32);
while integer(ContinueLoop) <> 0 do
 begin
  if ((UpperCase(ExtractFileName(FProcessEntry32.szExeFile)) = UpEFN)
      or (UpperCase(FProcessEntry32.szExeFile) = UpEFN)) then
   begin
    result := FProcessEntry32.th32ProcessID;
    ffound:=true;
    break;
   end;
  ContinueLoop := Process32Next(FSnapshotHandle, FProcessEntry32);
 end;
CloseHandle(FSnapshotHandle);
if not ffound then
 ShowMessage('notepad.exe is not runing');
end;

const DllName = 'ShowMe.dll';

var
PID: dword;

begin
SetSeDebugPrivilege;
PID:=GetPID('notepad.exe');
if (PID>0) then
 Load_DLL(DllName, PID);
end.

library ShowMe;

uses
 Windows, Dialogs;

begin
try
 ShowMessage('dll is load');
except
end;
end.

Load_DLL(PChar(ExtractFilePath(ParamStr(0)) + DllName), PID);

begin
SetSeDebugPrivilege;
PID:=GetPID('notepad.exe');
if (PID>0) then
 begin
  Load_DLL(PChar(ExtractFilePath(ParamStr(0)) + DllName), PID);
 end;
end.

lpStartAddress:= GetProcAddress(GetModuleHandle('kernel32.dll'), 'LoadLibraryW');

const DllName = 'E:\projects\DLL Injecting\dll\ShowMe.dll';
//конкретный путь к проекту с dll

Load_DLL(DllName, PID);

DllPath: AnsiString;