Mechanical blood pressure monitors are used in hospitals.
Pressure is measured by listening to the noises that come from our blood vessels. The meaning is this: we put on a cuff, squeeze and pump it up, thereby squeezing the vessels and arteries, as a result of which the blood stops running through them.
Then you slowly lower this cuff, the pressure decreases, and the blood begins to leak out. It is these small jolts, or noises, that are heard in a stethoscope.
Such blood pressure monitors are used, as a rule, in hospitals, because they are the most accurate.