Here are some examples of what can be done with a smartphone and a macro lens or microscope lens attachment.
Macro smartphone photography
Micro smartphone photography
Macro smartphone video
Micro smartphone video
As smartphone microphotography grows in popularity, we may see more microscopic art being developed. The master of microscopic art is William Wigan, who creates sculptures in the eye of a needle. Of course, Wigan uses an actual microscope, but I would not be surprised to see artists begin to create microscopic art using smartphones.