Dark sectors are ubiquitous in physics beyond the Standard Model (SM), and may play a role in explaining many of the long-standing problems of the SM such as the existence of dark matter or the electroweak hierarchy problem. By definition, dark sectors are not charged under any of the known forces. Discovering their possible existence is thus challenging. I will describe how a a broad program combining particle, nuclear and atomic physics experiments can effectively probe a large region of the parameter space. I will show how the unique signatures of such physics can already be searched for with existing/planned experiments, including neutrino-proton fixed-target experiments and precision atomic measurements.