procedure TForm1.Button1Click(Sender: TObject);
begin
  button1.caption:='ура!заработало!'

end;

procedure TForm1.Button2Click(Sender: TObject);
begin
      button2.caption:='и тут заработало!'   


пример 2
unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
begin
  button1.caption:='ура!заработало!'

end;

procedure TForm1.Button2Click(Sender: TObject);
begin
      button2.caption:='и тут заработало!'
end;

procedure TForm1.Button3Click(Sender: TObject);
    var
      funt,pud, kg: real;
begin
      pud:=StrToInt(Edit1.text);
      funt:=StrToInt(Edit2.text);
      kg:=pud*16.38+funt*16.38/40;
      label4.Caption:='в килограммах'+floatToStr(kg);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin

end;

end.