JSFiddle - React, Tailwind, and code Playground

HTML

<input type="time" id="timeOfCall">
<input type="time" id="timeOfResponse">
<button>CLICK</button>
<input type="time" id="delay">

JavaScript

$('button').on('click', function () {
    var timeOfCall = $('#timeOfCall').val(),
        timeOfResponse = $('#timeOfResponse').val(),
        hours = timeOfResponse.split(':')[0] - timeOfCall.split(':')[0],
        minutes = timeOfResponse.split(':')[1] - timeOfCall.split(':')[1];
    
    minutes = minutes.toString().length<2?'0'+minutes:minutes;
    if(minutes<0){ 
        hours--;
        minutes = 60 + minutes;
    }
    hours = minutes.toString().length<2?'0'+hours:hours;
    $('#delay').val(hours + ':' + minutes);
});