How do you tell if someone is tracking your phone on Find My Friends?
No. When sharing location with friends using Find My Friends, the other person doesnt know how many times their friends have looked them up. They dont get any notification or there isnt any log of lookup incidents made available to them. The location is sent from the friends device only when you request to see it.
Can I tell if someone is tracking me on Find My?
There is absolutely no way to know if anyone is tracking you using Find my iPhone. The ONLY way someone can track you is if they know your Apple ID and password, so if you suspect someone is tracking you simply change your password and they wont be able to.
When using Find My phone to track someone do they know?
Its sole job is to track people and would be the best approach to this. Expanding on my last comment to link to the question, Find My Friends does not notify the person when you are tracking them if you are on each others friend lists.