How to make a plugin to add adsense code below header?

In additional to the ad at the bottom of the mobile page, I also hard coded into the end of the minileven header another adsense ad. The problem is that when Jetpack updates, the code gets removed.

With regular themes I would use a child theme to address that. Is there a simple way to add code to the end of the header file with a plugin?

Thanks.

https://www.ads-software.com/plugins/jetpack-mobile-theme-ads/