MS Word — Use of dynamic captions

In MS Word you can put caption numbers with bitmaps. If you paste a bitmap before another, the capture number of the first bitmap will change to reflect that it is now number 2 instead of number one.
I would like to refer to this caption number in the text, & would like for the reference to change if the caption number changes.
I have looked at the use of “fields” to see if there is functionality there, but I did not find any.
Did I miss something in the use of “fields”? Or is the functionality somewhere else? Or not there at all?