Multi select DropDownList issue please help

Question

Hello sir i have a dropdownlist i want to select multiple employees from the dropdown list this is working.

 

Now i want to assign the selected value in a string or hiddenfeild. Please help

 

here is a drop down list which is bind dynamically

<asp:DropDownList runat="server" ID="ddlemployee" class="form-control select2" multiple="multiple"
data-placeholder="Select a State" >
</asp:DropDownList>

DataTable dtMember = objaccess.GetDatatable("select Emp_no,Emp_Name from Emptable");
if (dtMember.Rows.Count > 0)
{
ddlemployee.DataSource = dtMember;
ddlemployee.DataValueField = "Emp_no";
ddlemployee.DataTextField = "Emp_Name";
ddlemployee.DataBind();
}