It is possible to break your hymen by getting fingered if the finger was placed far enough into the Vagina to reach the Hymen.
Your hymen is located deep inside the Vagina and sometimes your Hymen won't be broke when getting fingered but in some cases the Hymen can and will be broke when you get fingered as long as the finger gets deep enough inside the Vagina to reach the Hymen and break it.
Once you break your Hymen you've lost your Virginity.