It’s pretty hard unless you hear the verb in question being used.

You can hear a particle verb because the particle will be stressed.

For example, “komma ihåg” means “remember” (actually I believe the direct translation is something like “come to mind” from the olden days but no one ever thinks of that, everyone only ever thinks “remember” when they hear it). Anyway, whenever you hear it you’ll hear speakers say “komma ihåg” with stress on “ihåg”. The same can be heard with “tycka om”, with “om” being stressed.

If the preposition is not stressed, it is just a preposition, not a particle, and hence it’s not a particle verb.