I don't have any need to write down the exposure info for every frame I shoot.
What I take notes for are to remember dates and locations of things I photograph, and any other info about the person, place or thing that I want to remember. I use Evernote for that. Evernote is nice because I can use it on android, iOS, Mac and Windows. I can even attach photos to the notes, so I can see the photos the notes are about!
It is, depending on the features you want, either Free, $3,99 a month, or around $7 a month. I'm using the $3.99 a month version.