  We conduct frequency comparisons between a state-of-the-art strontium optical
lattice clock, a cryogenic crystalline silicon cavity, and a hydrogen maser to
set new bounds on the coupling of ultralight dark matter to Standard Model
particles and fields in the mass range of $10^{-16}$ $-$ $10^{-21}$ eV. The key
advantage of this two-part ratio comparison is the differential sensitivities
to time variation of both the fine-structure constant and the electron mass,
achieving a substantially improved limit on the moduli of ultralight dark
matter, particularly at higher masses than typical atomic spectroscopic
results. Furthermore, we demonstrate an extension of the search range to even
higher masses by use of dynamical decoupling techniques. These results
highlight the importance of using the best performing atomic clocks for
fundamental physics applications as all-optical timescales are increasingly
integrated with, and will eventually supplant, existing microwave timescales.
