You can use the MouseDown event and check if it is right
void button1_MouseDown( Object^ /*sender*/, System::Windows::Forms::MouseEventArgs^ e )
{
// Update the mouse path with the mouse information
Point mouseDownLocation = Point(e->X,e->Y);
String^ eventString = nullptr;
switch ( e->Button )
{
case ::MouseButtons::Left:
eventString = "L";
break;
case ::MouseButtons::Right:
eventString = "R";
break;
case ::MouseButtons::Middle:
eventString = "M";
break;
case ::MouseButtons::XButton1:
eventString = "X1";
break;
case ::MouseButtons::XButton2:
eventString = "X2";
break;
case ::MouseButtons::None:
default:
break;
}
//Process Here...
}