Attached is one of our group publications on nanoliposomal co-encapsulation of nucleic-acid drugs and divalent metal nanoparticles. You may find it useful in answering your query:
Mozafari, M. R., & Omri, A. (2007). Importance of divalent cations in nanolipoplex gene delivery. Journal of pharmaceutical sciences, 96(8), 1955-1966.
One way can be using bio-conjugation techniques. Conjugate lipids/phospholipids using anchoring functional groups on your nanoparticles. If the density of nanoparticle is higher than lipids, it would be difficult to encapsulate nanoparticle in the liposome. So you have to consider various factors for encapsulation, including hydrophobicity, density, size etc of your nanoparticle for encapsulation in a liposome.