WordPress has a builtin functionality that allows you to easily add captions for images. Captions are a good way to display extra information about the image or show copyright information. After you upload an image, WordPress media uploader allows you to provide image title, description, and caption. You can also add captions to existing images by editing the image.
Caption through shortcode
There is also a way to do it with a shortcode:
<image> Caption
For a full documentation of the caption shortcode read https://codex.wordpress.org/Caption_Shortcode