I just googled "driver day tour Paris" and got several hits and links. I often hire in-city drivers for a client of mine, and it is less of a big deal than some think. Perhaps the OP is elderly or mobility impaired...

That said, my client who uses drivers does not use them in Paris because it's just so easy to get around. If he did, I would give you a name.

But really it wouldn't be that hard to find one. Tripadvisor is a good source for reviews and recommendations for such a driver in Paris.