Add the button1_MouseMove(object sender, MouseEventArgs e) handler and your button would fly too 😄
private void button1_MouseMove(object sender, MouseEventArgs e)
{
Random r = new Random();
int bx = r.Next(10, ClientSize.Width - button1.Width);
int by = r.Next(10, ClientSize.Height - button1.Height);
button1.Location = new Point(bx, by);
}