The keyboard could be showing or dismissed it doesn’t matter. To enter the preview mode while Voiceover is running, Do a three-finger swipe to the left while the cursor is anywhere in the note. This is great, because it enables a means of scrolling effectively through long notes, which is generally not easy on IOS. This means that if your Markdown contains headings, in the preview you can move between headings in the same way you would on a webpage. But Simplenote makes switching to a preview of your Markdown text easy. That's not particularly unusual, lots of notes apps do have Markdown support these days. This app supports writing in Markdown, which is basically a user-friendly way of representing various kinds of markup like headings, lists, links, checkboxes etc. You can read all about it here but I will focus on two features I find most useful as a Voiceover user of the IOS app in particular. Your notes sync seamlessly between platforms, no extra steps required. It's free and are versions for IOS, Android, Windows, Mac, Linux and in a browser. As a Voiceover user, the Simplenote app by Automatic is an app I use daily.

Simple note taking app windows