My understanding of
modprobe is that it is a command to load kernel modules.
Based on this, I'm wondering what the meaning of word probe is in general English?
probe is from the Latin probare, which means "to test, to examine". It is used to mean an inquiry, or thorough examination, probing tends to imply getting inside something to reveal what is hidden, the truth.
A probe, as an object, is a device used to look within something else, to see what is veiled in some respect.
In the case of
modprobe, the purpose of the command (see the man page) is to add/remove modules from the kernel at runtime, which often requires an initial "probe" of the internal hardware in order to detect hardware that drivers may rely on, or indeed checking for dependencies to load within the "internals" of the system.