How can you tell if the input or output of a logic device is HIGH or LOW?

A: using a multimeter or scope it can be verifies the states of a logic device either as '1' or a '0' which translates to true = hi [volts] = '1' and '0' as low [volts] = '0'. '0' is a false state and '1' is a true state. Must add that the voltmeter will not decipher hi or low if toggling