I'd recommend using the Fitbit App and then getting a cheap pedometer to wear when you can't have your phone with you. They're pretty accurate and do the job! You could just manually enter your steps into the FitBit app once you have your phone back.
This one has good reviews and is on sale for $9.99 today! Hope this helps...
https://www.amazon.com/PINGKO-Multi-function-Portable-Pedometer-distance/dp/B019DD7HLY/ref=sr_1_72