Oh, I have no clue, I imagine it's negligible but it's possible.
Like most mining in general you probably won't make positive net gains unless you scale it, and join pools.
It might be beneficial if you run it off of solar, or some other cost efficient electricity method.
I only mention it because one cpu = one vote with monero, anyone can mine it whereas with Bitcoin in the hopes to be profitable you need an Asic.
I think there's a coin specifically designed for phone mining called pi coin, or something like that but I haven't looked much into it.