‘Save settings’ (submit button) ISSET

You question is not well explained, what you want to achieve, here is the suggestion,

you can add JS event ONClick into you submit button and define the JS function according to your goals, (for example you want to count submit button click)

<script type="text/javascript">
var clicks = 0;
function onClick() {
    clicks += 1;
    document.getElementById("clicks").innerHTML = clicks;
};
</script>
<form method="post" action="options.php">
   . 
   . 
   .
<button type="button" onClick="onClick()">Submit</button>
<p>Clicks: <a id="clicks">0</a></p>
 </form>