Move caption overlay box beneath an image (All Themes)

Many of our themes include styling for a caption overlay box. This means that if you use the caption feature on any image, the content you input would automatically appear on top of the image. Here's what this looks like.

Some users may wish for captions to format more traditionally, underneath an image. Here's what this Code Hack looks like in action:

And here's the code you need to implement it!