How to measure whether there is water underground by drilling wells?

Before drilling a well, the drilling team will use professional water finding instruments to determine the water level of the well. In addition to this method of measuring with instruments, there are also some geographical knowledge judgment methods: when the weather is generally hot, if a place feels particularly humid, there is likely to be well water here. Especially when it rains, it is generally difficult to remove the accumulated water in these places. When the weather is cold, the accumulated water on the road will freeze, but you find that the accumulated water somewhere will not freeze. Then most places here will also have underground water sources. If it is in autumn, foggy days often occur. And sometimes we find that the fog in a certain place is particularly serious. Then there must be water around here.