For Delphi 2009+ you can use anonymous method (closure):
MessageDlg('Are you delete this record?', mtConfirmation, mbYesNo,
procedure(AResult: Integer)
begin
case AResult of
mrYes: UniEdit1.Text := 'YES'; // UniMemo1.Lines.Add('YES');
mrNo : UniEdit1.Text := 'NO'; // UniMemo1.Lines.Add('NO');
end;
end);