Saber si se desconecta un mouse usb

[[cHackAll]]

Código Delphi [-]
procedure TForm1.Button1Click(Sender: TObject);
var
 hKey: Windows.HKEY;
 cbData, Count: Cardinal;
begin
 cbData := SizeOf(Count);
 RegOpenKey(HKEY_LOCAL_MACHINE, 'system\currentcontrolset\services\mouclass\enum', hKey);
 RegQueryValueEx(hKey, 'count', nil, nil, @Count, @cbData);
 RegCloseKey(hKey);
 
 ShowMessage(IntToStr(Count));
end;