How to trigger Novocall callback with a click of your existing buttons.
Step 1 - Select CSS Click Trigger
Navigate to "Inbound" > "Widget Settings" > "Behavior" tab
Step 2 - Add in CSS
Take your button's CSS element and add it in here. Switch in the trigger option.
Step 3 - Test
Refresh your site and test the button/element again. You'll see the Callback Popup upon click.