Ultralight boson fields can form ``boson clouds'' around black holes through the superradiant extraction of rotational energy of spinning black holes. These clouds can reach energy densities significantly higher than that of dark matter, turning black holes into powerful potential detectors for ultralight bosons. After briefly reviewing this process, in this talk I will discuss how the Event Horizon Telescope and its future upgrades could be used to study the existence of ultralight bosons. My talk will be based on the review that the ``ngEHT Fundamental Physics Science Working Group'' recently put together: arXiv:2312.02130 (Sec. 4).