WinForm Method to Override "Close" Button in Upper Right Corner

protected override void WndProc(ref Message msg)
{
 const int WM_SYSCOMMAND = 0x0112;
 const int SC_CLOSE = 0xF060;
 if (msg.Msg == WM_SYSCOMMAND && ((int)msg.WParam == SC_CLOSE))
 {
  // Click close button on winform upper right 
  // Add wanted logic processing
  return;
 }
 base.WndProc(ref msg);
}

Link Address:Method to judge close event comes from user clicking “Close” button in upper right corner in WinForm