[Asmoday74]

ручками в обработчике onChange TComboBox. Что-то вроде

Код:

type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    Image1: TImage;
    ImageList1: TImageList;
    procedure ComboBox1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

...

procedure TForm1.ComboBox1Change(Sender: TObject);
begin
  if ComboBox1.ItemIndex<>-1 then
  begin
    ImageList1.GetBitmap(ComboBox1.ItemIndex,Image1.Picture.Bitmap);
    Image1.Repaint;
  end;
end;