I wrote a post on this a few years ago, explaining how to use HTML to wrap text around an image in WordPress. Even though you can do text wrapping and image alignment within WordPress, I still prefer to write the HTML myself as I get better results and I get to decide what my captioned image looks like.
But as the HTML for this is a bit tedious, it is a pain to have to type the code out each time, so I gave up doing image captions. However, we recently built a WordPress plugin to do it. The plugin was released yesterday, so please go and download it, and let me know if it works for you.
CaptionPix WordPress Plugin – For Image Placement And Captioning
The name of the plugin is CaptionPix and you can download it from the WordPress Plugins Repository :