iPhone

https://support.apple.com/en-us/HT210336 - how to scan documents on your iphone or ipad using the Notes app

https://www.youtube.com/watch?v=zgUSYp4pwXo – video from Apple for above

Android

https://support.google.com/drive/answer/3145835?co=GENIE.Platform%3DAndroid&hl=en - how to scan on an Android using Google Drive.