Understanding dark energy (DE) and dark matter (DM) is one of the most pressing problems in physics. Recently, scalar fields have become popular candidates to constitute the dark sector. As the corresponding particles have small masses and wavelengths in the sub-mm range, force metrology has proven to be useful in this respect. Over the past decade, tight limits on most candidate models have been set. However, better experiments are required to finally exclude them. It remains unclear why the contribution of the most obvious DE candidates – vacuum fluctuations – is so small, but their effect can be measured as Casimir force. The latter has been investigated experimentally for 25 years. Still, questions regarding the interaction of vacuum fluctuations with matter remain. Recently, progress was made in theory, renewing the demand for high-accuracy data. If one of the proposed (scalar) interactions exists, it should give rise to non-Newtonian forces between test bodies. Using force metrology, we can answer the question if such forces exist within the precision of the measurement, and even exclude some models entirely. In Casimir physics, a recent theoretical approach could lead to an answer to the question if propagating and evanescent waves interact differently with matter. Cannex is presently the only metrological force setup implementing the ideal geometry of plane parallel plates. This geometry allows for superior sensitivity regarding interfacial forces at the level of the gravitational interaction between the test objects. In addition, it allows to address physical questions at distances hitherto unavailable to other experiments. After a recent proof of principle, the setup shall now be improved to reach sensitivities of 1 nN/m² and 1 mN/m³ for the force per area and its gradient, respectively, between macroscopic parallel plates, with perfect control over all relevant parameters. Further improvements are possible in the future. Cannex is the first experiment to measure Casimir forces at high precision at separations larger than 10 μm. This allows us to perform the first detailed investigations of the effect in the so-called thermal regime, and to bridge the gap between Casimir experiments and Cavendish-type torsion balance experiments. In this niche, Cannex covers a unique parameter space for a large variety of DM and DE models, including symmetrons and chameleons, as well as gravity.