entire site last updated function

I would like to display the last time any page, post, or anything was updated on my entire website that’s using wordpress. I just want it to display on the home page.

To be clear, I want to display the date/time anything on the site was updated, not just the current page.

The New York Times has what I want, when an article is written or updated somewhere on the site, the “Last Updated” time changes on the home page. I’ve heard it’s very simple to do, but I just can find an answer. Help is greatly appreciated!