I don’t keep the written notes. But if I did, the process would be about the same. Write the notes, scan them in using the Rocketbook app – or the Adobe scan app (also free) and then store the notes.
Both of those apps use a scanner, so, it’s not “taking pictures” as much as holding phone steady and letting it collect the data. Not sure how else you’d digitize the information other than letting a camera at it.