how to do combobox selected item change .

private void showSelectedButton_Click(object sender, System.EventArgs e) {
    int selectedIndex = comboBox1.SelectedIndex;
    Object selectedItem = comboBox1.SelectedItem;
 
    MessageBox.Show("Selected Item Text: " + selectedItem.ToString() + "\n" +
                    "Index: " + selectedIndex.ToString());
}