Different but the greeks when besieged were known to drive stakes of brass with a thing brass plate above ground attatched to it at intervals, then they could see the vibrations from anyone tunneling under, what do they call it, sapping, they dig under, then burn the supports and collapse a section of wall to breach the city.

One incident the greeks made a chemical weapon out of chicken feathers and chicken shit and charcoal and lit it and threw it down there after they counter tunneled into them after seeing their vibrations.

Radar was developed before WW2. It was just really expensive, so analogue systems (eg, mk1 human eyeball, and this monstrosity) were used to supplement.