Is it possible to swap a featured image for some code?

Hi,
My problem is I’d like to use some embedded code (which shows a photo using the Zoom.it software) as my featured image.
It’s probably best that I show you what I’m trying to do..
Go to this link:
https://www.joiningphotography.com/bigger-than-a-big-bag-of-big-things/
What I’d like to do is instead of the ‘Blog’ image at the top of the page, which is the featured image, I’d like to use the image in the post which can be zoomed.
I know that when you add an image you can specify a URL, but there doesn’t seem to be the facility to use embedded code..
The code that points to the image is this:
<script src=”https://zoom.it/JW21.js?width=auto&height=400px”></script&gt;

Any help would be greatly appreciated.. ??