IDictionary<int, string> comboDictionary = new Dictionary<int, string>();

        private void Form1_Load(object sender, EventArgs e)
        {
            /*comboBox1.Items.Add("name");
            comboBox1.Items.Add("cni");
            comboBox1.Items.Add("ip");
            comboBox1.Items.Add("maroc");
            comboBox1.SelectedItem = 0;
            */
            comboDictionary.Add(1, "first");
            comboDictionary.Add(2, "second");
            comboDictionary.Add(3, "third");
            comboBox1.DataSource = comboDictionary.ToList();
            comboBox1.DisplayMember = "Value";
            comboBox1.ValueMember = "Key";

        }

        private void Button1_Click(object sender, EventArgs e)
        {
            //MessageBox.Show(comboBox1.Items[comboBox1.SelectedIndex].ToString());
            comboBox1.Items[comboBox1.SelectedIndex].ToString();
            var control = ((KeyValuePair<int, string>)comboBox1.SelectedItem).Key;

           MessageBox.Show(control.ToString());

        }