procedure TForm1.Button1Click(Sender: TObject);
var
  hTaskBar : THandle;
begin
// If you want to detect a letter you must be use the ascii code.

//detect the "a and the A letter".
if GetasyncKeyState(65)<>0 then Caption:='A';

if GetasyncKeyState(97)<>0 then Caption:='a';

// If you want to detect the left button of the mouse use:
if GetasyncKeyState(1)<>0 'mouse
end;

//To detect a hey you must be use the Virtua key codes..

if GetasyncKeyState(vk_space)<>0 then Caption:='Spacebar';