Note the big difference in amount of vibration if you hold a sensor and shake it, or if you bury it in the ground and expect to see vehicles at 100m distance.

If your multimeter can see voltages in the volt range when shaking the sensor - do you think it can see mV or uV signals from minute vibrations?

Obviously, you must have alrady considered what type of electronics you need to use with this sensor. And exactly how large signals the sensor gives for the type of vibrations you want to measure.