I started using Apple Notes for most of my needs because as much as I love playing with notes apps my needs are pretty meager. One thing that is a bit annoying about Apple Notes though is there isn’t an “easy” way (in other words something like right-clicking on the note) to get a deep link to a note to paste in other app. Drag and drop doesn’t work either. The solution however is pretty simple: in the body of the note add a link to the note itself and copy the link. Done.
On the Mac you can do CMD-K and search on the note title. On the iPhone you just add a link via the editing toolbar and do the same thing. I expect on the iPad it can work either way depending on whether you have a keyboard attached or not.
One thing I found using this with Things 3 is that the link isn’t clickable unless you turn it into a Markdown link. That Also means in the case of Things 3 that the link has to be in the note section where Markdown formatting works. I found the same thing required for any of the Markdown editors I use.
In OmniFocus 4 you have to create a link using the edit menu. This probably is true for other apps as well.