This way
HTML
<asp:ScriptManager runat="server">
</asp:ScriptManager>
<cc1:TimeSelector ID="TimeSelector1" runat="server" AllowSecondEditing="true">
</cc1:TimeSelector>
<asp:TextBox ID="txtTime" runat="server" />
<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="Submit" />
Code
protected void Submit(object sender, EventArgs e)
{
DateTime time = DateTime.Parse(string.Format("{0}:{1}:{2} {3}", TimeSelector1.Hour, TimeSelector1.Minute, TimeSelector1.Second, TimeSelector1.AmPm));
txtTime.Text = time.ToString("hh:mm:ss tt");
}
Screenshot
