uses Registry;

///

function TForm1.GetDeskPath(): string;
const
  regPath = '\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders';
var
  Reg: TRegistry;
  strFolders: string;
begin
  Reg := TRegistry.Create;
  try
    Reg.RootKey := HKEY_CURRENT_USER;
    if Reg.OpenKey(regPath, false) then begin
      strFolders := Reg.ReadString('Desktop');
    end;
  finally
    Reg.Free;
  end;
  result := strFolders;
end;