UNIT1.pas:
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs,Unit2;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  form1.Caption:=jacekkw;
end;

end.

UNIT2.pas:
unit Unit2;

interface

implementation
function jacekkw:string;
begin
  result:='JacekKw';
end;

end.