Depending on which article and study you find, there are opinions that go both ways. Some say you get more reach with hashtags in the caption, some say you get more with the hashtags in the comments since it’s hidden.
It really depends on your audience and what kind of content you are posting. It also depends on what hashtags you are using (are they relevant), and how many.
In theory, the hashtags will work the same way whether in the captions or in the comments. The real only way to be able to tell is testing and see how your audience reacts to it. Try it for a month and see what happens.