There is usually an attenuator on the probe to attenuate the measurement signal. Its multiple is generally 10 times. 1V signal, display1000 mv. Some oscilloscopes can automatically identify the state of the probe and display the correct value.

The probe uses the characteristics of high impedance to ensure that the circuit is not interfered by the measuring part, but sometimes we need to measure some circuits through low impedance test. For example, the RF output circuit with 50 ohm impedance is a key problem for machines with 50 ohm impedance measurement function; But for ordinary oscilloscopes, the probe is not suitable for measurement at this time. You need to match the BNC tee with the 50 ohm terminal resistance and connect it directly to the 50 ohm output terminal at the other end.