You can use onChange even on the textbox and use jQuery change label text.
On the other hand, if you want to do it more nicely knockout, angularJS kind of frameworks offer you
two way bindings[
^].
<!DOCTYPE HTML>
<html>
<body>
<label id="label" for="inputText">Label</label>
<input type="text" id="inputText" onchange="changeLabel();">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script>
function changeLabel()
{
$("#label").text($("#inputText").val());
}
</script>
</body>
</html>