Please follow below steps achieve the same:
Step1: Create a custom class for ComboBox Listitem
public class ComboboxItem
{
public string Text { get; set; }
public object Value { get; set; }
}
Step2: Create object of custom class(
ComboboxItem) and add those objects to ComboBox
ComboboxItem item = new ComboboxItem();
item.Text = "year1";
item.Value = "2015";
comboBox1.Items.Add(item);
item = new ComboboxItem();
item.Text = "year2";
item.Value = "2016";
comboBox1.Items.Add(item);
comboBox1.DisplayMember = "Text";
comboBox1.ValueMember = "Value";
Step3: On button click get the selected value of ComboBox
private void button1_Click(object sender, EventArgs e)
{
label1.Text = (comboBox1.SelectedItem as ComboboxItem).Value.ToString();
}