I often use my phone as a notepad by photographing things (timetables, shelf-labels in shops, etc.) but sometimes a scanner is what we really need.
Adobe has produced an Adobe Scan app to do the job. You do need an Adobe ID but that is free. It captures an image using the camera and this can be tweaked. The image is then saved as a PDF (that’s quite big)and uploaded to your account on the Adobe Cloud.
I’m still trying to work out what does this do that we can’t do using the camera and a USB cable?