how can i find out who a familiar belongs to?

is there a way to figure out who a familiar belongs to using a spell or some in book magical/nonmagical means?

Speak with animals in a zone of truth

Quote from Yhulths >>

Speak with animals in a zone of truth

 
Speak with Animals only works on Beasts.

Familiars may take the form of a beast but are not beasts - they would be fey, fiend or celestial depending on which the caster chose.

Familiars not created through spells like Find Familiar or Flock of Familiars are usually not beasts, either, as the only non-spell familiars, going by RAW, are Aberration, Dragon or Fiend.

Detect thoughts. Suggestion. Try and bribe the familiar. Follow it (however you want, arcane eye, on foot, whatever), put it to sleep and use the dream spell, modify memory and convince it you’re it’s master, then when it’s master tries to talk to it you ask it who it hears

There’s many different ways to go about it. A lot comes down to luck and what your DM will allow.

You could always ask it. Even if it may not answer, there's a good chance the one controlling it will know you are asking.

Grab it and see who comes running over. Not elegant, but it could work. 
Or just look around. Odds are the owner is within 100 feet. 

Quote from TexasDevin >>

You could always ask it. Even if it may not answer, there's a good chance the one controlling it will know you are asking.

 This was my first thought as well. If it's a familiar on its own, there's better than a decent chance its owner is perceiving through it, so just ask the familiar like you're talking on the intercom to someone's apartment. :)

It's an expensive solution, but I would probably allow a casting of Legend Lore on the familiar to reveal information about the owner if you really wanted to burn a 5th-level spell slot.

Quote from 5PercentGlory >>

Detect thoughts. Suggestion. Try and bribe the familiar. Follow it (however you want, arcane eye, on foot, whatever), put it to sleep and use the dream spell, modify memory and convince it you’re it’s master, then when it’s master tries to talk to it you ask it who it hears

 So what you are saying is, use a social engineering attack. :-)