unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm2 = class(TForm)
    Label1: TLabel;
    Button1: TButton;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }

  public
    { Public declarations }
  end;

 //второй поток----
  TMyThread = class(TThread)
    private
    { Private declarations }
  protected
    procedure Execute; override;
  end;
 //------------------

var
  Form2: TForm2;
   MyThread: TMyThread;//второй поток

implementation

{$R *.dfm}

procedure TMyThread.Execute;
var a2:integer;
begin
a2:=1;
//Form2.Label2.Caption:=IntToStr(a2);
end;

procedure TForm2.Button1Click(Sender: TObject);
var a1,a2:integer; 
begin
MyThread:=TMyThread.Create(False); //запускаем второй поток
a1:=5;
Label1.Caption:=IntToStr(a1);    
Label2.Caption:=IntToStr(a2);
end;

end.