  Reconfigurable metasurfaces offer great promises to enhance photonics
technology by combining integration with improved functionalities. Recently,
reconfigurability in otherwise static metasurfaces has been achieved by
modifying the electric permittivity of the meta-atoms themselves or their
immediate surrounding. Yet, it remains challenging to achieve significant and
fast tunability without increasing bulkiness. Here, we demonstrate an
ultra-thin tunable metalens whose focal distance can be changed through
optomechanical control with moderate continuous wave intensities. We achieve
fast focal length changes of more than 5% with response time of the order of
10$\mu$s
