Hi SajidHussa,
Check this sample. now take its reference.
UserControl.ascx
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs"
Inherits="WebUserControl" %>
Enter Mobile No :
<input id="txtMobileNo" type="text" placeholder="Enter Your Registered Mobile Number" />
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
$("[id*=btnSubmit]").on("click", function () {
var number = $('[id*=txtMobileNo]').val();
alert(number);
});
});
</script>
<form id="form1" runat="server">
<div>
<uc1:UserControl ID="UserControl1" runat="server" />
<br />
<asp:Button ID="btnSubmit" Text="Submit" runat="server" />
</div>
</form>
</body>
</html>
Screenshot
