Recently, 5d¹ and 5d² double perovskites have attracted increasing attention as a new platform for multipolar physics. Besides the strong spin-orbit coupling, the lattice degrees of freedom play a crucial role in the 5d systems. The lattice degrees of freedom exhibit a strong quantum nature in the form of the dynamic Jahn-Teller effect characterized by orbital-lattice entanglement. In this presentation, we focus on the family of 5d¹ double perovskites and discuss the nature of the multipolar ordered phases. We present the fingerprints of the dynamic Jahn-Teller effect in the resonant inelastic x-ray scattering (RIXS) spectra and discuss the orderings of the dynamic Jahn-Teller centers in 5d¹ double perovskites.