Microsoft has a very good scanning app called Lens|PDF Scan. This handy iOS app allows you to use your iOS camera to scan in documents, business cards, sticky notes, receipts and whiteboards and make them readable for later use and reference.
You can even share the scan with other apps.
The app handles conversion of handwriting using OCR as well. Obviously, the better the handwriting, the better the recognition. However, the app is a great tool to capture and digitize external notes and insert them into other apps for later use.
Screencasts online has a preview screencast tip on using Lens.
If you are looking for a way to capture and digitize paper or other notes, consider Lens.