How to capture a selected item from a combobox filled from a BD

I need help with a bit of code. It turns out that I have a combobox that I fill using a database:

private void frmMain_Load(object sender, EventArgs e)
    {
        //TEXT BOX DISABLED
        txtDv.Enabled = false;
        txtNombre.Enabled = false;
        txtApellido.Enabled = false;
        txtCorreo.Enabled = false;
        txtTelefono.Enabled = false;

        //LLENAR COMBOBOX DESDE BD
        using (SqlConnection conn = new SqlConnection("Data Source = DESKTOP-0PSJQKP; initial Catalog = BDControlEPP; User = sa; Password = a123456"))
        {
            try
            {
                string query = "select idItem, nombreItem from tblItems";
                SqlDataAdapter da = new SqlDataAdapter(query, conn);
                conn.Open();
                DataSet ds = new DataSet();
                da.Fill(ds, "Items");
                cbItems.DisplayMember = "nombreItem";
                cbItems.ValueMember = "idItem";
                cbItems.DataSource = ds.Tables["Items"];

            }
            catch (Exception)
            {

                throw;
            }
        }

    }

And I need to capture the selected item in the combobox with an ADD button that I have beside it, plus a text box next to it that would indicate the amount I want of that item and insert it into a Listview in the same form.

I remain attentive to any response, greetings!