The MicroBooNE detector is a liquid argon time projection chamber that has been operating in Fermilab's neutrino beamlines since 2015. Although primarily designed to measure neutrino interactions, the high intensity meson beamlines coupled with the high resolution detector and excellent high-multiplicity electron, muon or pion identification, allows other New Physics searches, such as for decays of long-lived particles. We have recently released competitive limits on a Higgs-Portal scalar model, where a new scalar field mixes with the Higgs boson, can be produced in kaon decays, and decay to lepton or pion pairs. This model attracted some interest due to its ability to explain an excess of neutral kaon decays reported by the KOTO experiment. In this talk I will present these recent MicroBooNE limits on this and similar models, and will give an outlook of further searches that can be perfored in this and future Fermilab neutrino experiments.