type
  TMyThread: class (TThread)
    Status: String;

    procedure Execute; override;
    procedure VCL_Result;
  end;


procedure TMyThread.Execute;
begin
  Status := 'fange an';
  synchronize (VCL_Result);

  // Der Threadcode
  Sleep(2000);

  Status := 'fertig';
  synchronize (VCL_Result);
end;

procedure VCL_Result,
begin
Form1.Label1.Caption := Status;
end;