I am a postdoc, applying for tenure track jobs in mathematics. I did my bachelor degree as a kid (was 14 when started). I wonder if I should/could mention this in my academic CV?
In my academic CV, I have included all my university education, which naturally includes my undergraduate degree.
I don't think it makes any difference that you started when you were 14. You came out with the same piece of paper as everyone else in the end up.
It possibly depends on where you are sending the CV. For a research position, it clearly indicates intelligence and thus probably would help or at least not hurt (as long as you don't overplay it). For more of a teaching job (e.g. at a 4-year college) I could see how it might potentially hurt: if you didn't have the typical high school math background you might have difficulty teaching students who have just come from that (with all of the gaps and weaknesses such a background so often entails).
Perhaps you can prepare two different versions of your CV, one that contains the parenthetical (started at age 14) and one that doesn't. For each job you apply to, make a judgment call about which one to send, taking into account both the job description and the nature of the school.
I was in a very similar situation: Started my BSc with 13, got it with 16 and was looking for a faculty level position in Math or CS [plenty of other things happened in between].
My CV does mention this. It never came up during an interview, or informal feedback, neither in a positive or negative way. I got a position.
Of course, this is just a single data point, but maybe it helps.