You can use this tool to see sensor measurements.
Tap the Sensors tab.
Select a sensor, you will see the measurements that the phone is making in real-time.
On the sensor bar, you will see icons for the different sensors which name will appear when selected (ambient light, sound intensity, pitch, accelerometer, magnetometer, compass)
Tip: Swipe the toolbar up or down for a better view.
If you want to add recordings of your sensors' measurements to your experiment journal, here is the full tutorial.