If your device has Bluetooth and it is not very very old, its Bluetooth version will be 4.x or higher (you can check it in your device specs). BLE was defined in 4.0. --> so my bet is that it will probably have BLE (besides other profiles)
By default, the phone BLE behaves as a Central. By scanning with the OS, you can see the peripherals that advertise themselves. Some standard devices (for instance, keyboards) are directly recognized by the same OS, which can seamlessly integrate them if the user chooses to do it.
Programmatically (with the needed libs for each case), you can make it work as a central, and, if the device allows for it (since API 21+, but not all devices support it, see
HERE ) make it work as a peripheral. For both cases you'll need to know which services/characteristics the other device has, in order to communicate with it.
I'd start with the
BLE (Central) example and just check if your device can detect the sensor.