Hi there.
you can use javascript codes:
HTML Code:
<asp:HyperLink runat="server" NavigationUrl="http://www.test.com" onclientclick="loadText(this);"></asp:HyperLink>
<input type="text" id="txtUrl" />
<script type="text/javascript">
function loadText(linkObj){
document.getElementById("txtUrl").value = linkObj.href;
return false; // avoid navigation
}
</script>