Responding to media buttons in Delphi

Question

I'm using Delphi Rio. My goal is to detect key press from the headset, as well as bluetooth remote shutter or every remote control buttons then the app responses and does a job. I tried to use KeyDown event but couldn't find the right way.

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char;
  Shift: TShiftState);
begin
  if key = {something} then
    begin
      //....
    end;
end;

could anyone help me to detect and response to different types of clicks from the headset and other remote controls like blutooth camera shutter.