Yes but it will be only client side i.e. JavaScript
<asp:TextBox ID="TextBox1" runat="server" onkeypress = "GetKeyCode(event)" />
<script type = "text/javascript">
function GetKeyCode(evt)
{
var keyCode;
if(evt.keyCode > 0)
{
keyCode = evt.keyCode;
}
else if(typeof(evt.charCode) != "undefined")
{
keyCode = evt.charCode;
}
alert("You pressed : " + keyCode);
}
</script>