Перехват событий свертывания или развертывания окна

private
  { Private declarations }
  procedure WMSysCommand(
      var Msg: TWMSysCommand); message WM_SYSCOMMAND;
public
  { Public declarations }
end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.WMSysCommand(var Msg: TWMSysCommand);
begin
    if (Msg.CmdType = SC_MINIMIZE) or
       (Msg.CmdType = SC_MAXIMIZE) or
       (Msg.CmdType = SC_RESTORE) or
       (Msg.CmdType = SC_CLOSE) then
    MessageBeep(0) ;
    
    DefaultHandler(Msg) ;
 end;