Best way to get sketch into notes

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I have started typing lecture/course notes into Voodoopad and for some of the things I do I need quick sketch diagrams in there and I am looking of ways to do it. Ideas so far:

1) Draw by hand and:
1.1) Take a photograph (possibly a sheet at a time and cut them up)
1.2) Scan them as above

2) Graphics tablet. If so what software would work well for this? I have photoshop/illustrator, but I think this would be overkill for a simple line drawing. Open to any recommendations.

Any others?