It all depends on whether you're wanted for a crime so you ran away, and yes the Police have the means to trace you thru your electronics. Police don't do an extensive search for runaways as it really isn't worth their time and most runaways get into something and get caught and found out .
FYI, it would really be extremely stupid to runaway nowadays as most end up in some sexual game group or as drug dealers and most will never survive otherwise out here, and would never get a job and this is if they don't get killed first thing.