Microsoft has been doing a lot of work to improve its Sticky Notes service. Back in September, it rolled out Sticky Notes 3.0, allowing users to sync their notes across devices. This was a major change, but with syncing later came OneNote integration, allowing users to view their notes from the web and from mobile phones.
As was teased a month ago, you can now add images to your Sticky Notes, although the feature is still pretty limited. As of right now, it's only available in OneNote Online, where you can access your notes on the web.
Unfortunately, the feature isn't available in the Sticky Notes UWP app just yet, although now that it's live on the web, it seems likely that Insiders will see the feature pretty soon. Hopefully, it won't be tied to the Windows 10 19H1 update, although that does seem unlikely.