While I’m not adverse to home automation, is this something you need in your life, or just want? I like my perimeter security too be simple and tight, extra complications make the security audit much harder.

Will your insurance stand up to home made remote control unlocking?

To answer your question, place the servo in a suitably large enclosure and practically any adhesive should work, e.g. 3mM command strips or even velcro or double sided sticky. When confident that this is what you want, use a screw.