https://www.theverge.com/2017/9/26/16362386/apple-ios-11-notes-document-scanner-how-to-use

One of the most useful tricks in Apple’s iOS 11 update is found inside the Notes app: it’s a document scanner. If there’s a business card, receipt, or any other document you want to save or mark up, this tool makes getting it on your iPhone or iPad dead simple. If you’ve been using a third-party app for this purpose until now — and there are several great ones — you can probably uninstall it in favor of Apple’s own solution. That’s what I did, anyway.

To try out Apple’s built-in scanner for yourself, open Notes. Inside of any note, hit the + symbol above the keyboard. The menu that comes up will offer a few options — this is also the tool you’d use to add a photo or sketch to your note — but the “Scan Document” option is the one you want.