Before iOS 11 you needed third-party apps to scan documents with iPhone and iPad. Now you can do it in the Notes app.
Open or create a document in the Notes app.
Tap on the document to open the keyboard.
Tap the plus sign above the keyboard and choose Scan Documents.
Point the iPad camera at the document. As soon as a document is detected, you will hear the camera shutter. Continue with all your documents.
Tap the document thumbnail to view it. In the preview, you can change between document types like color, black and white, grayscale and photo. You can also adjust the crop if the scanner didn't get it exactly right.
Tap Done when you are.
In Notes, you can markup or sign the document.