how to get multiple coloumns in listbox form combo box in c#.net

public void combo1sel()
{
SqlCommand com;
            SqlDataAdapter sda;
            DataSet ds;
            string str;
            var connectionString = ConfigurationManager.ConnectionStrings["newproject"].ConnectionString;
            SqlConnection cn = new SqlConnection(connectionString);

            str = "select contact_name +'              '+CAST(number as varchar(50)) as one from contact where contact_name='" + comboBox2.Text + "'";

            com = new SqlCommand(str, cn);
            sda = new SqlDataAdapter(com);
            ds = new DataSet();
            sda.Fill(ds, "contact");
            listBox2.DataSource = ds.Tables["contact"];
            listBox2.DisplayMember = "one";
            //listBox2.Text = "select";
            //listBox2.Text = "";
}

  private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            comboBox2.AutoCompleteMode = System.Windows.Forms.AutoCompleteMode.Suggest;
            var connectionString = ConfigurationManager.ConnectionStrings["newproject"].ConnectionString;
            SqlConnection cn = new SqlConnection(connectionString);
            cn.Open();
            try
            {
                SqlCommand cmd = new SqlCommand("select contact_name +'              '+CAST(number as varchar(50)) as one from contact where contact_name=('" + comboBox2.Text + "')", cn);
                SqlDataReader dbr;
                dbr = cmd.ExecuteReader();
               // checkedListBox1.Items.Clear();
                listBox2.Items.Clear();
                while (dbr.Read())
                {
                    //string eid = (string)dbr["eid"];
                    string name = (string)dbr["one"];
                    listBox2.Items.Add(name);
                  
                }