You can leave the physical keys at home with the August Smart Lock ($199 and up), which turns a door with a standard deadbolt into a "smart door." The device lets you unlock your office door with your smartphone and distribute virtual keys to coworkers or assistants who may need access. Unlike other smart lock systems, the August lock hitches onto the deadbolt mechanism from the inside, and it doesn't change the appearance of the door.
The optional August Connect ($79) feature lets your control the lock over the internet. And with the wireless August Smart Keypad ($79), you can unlock the door using a unique entry code. (If you want support for Apple's HomeKit, make sure you choose the appropriate updated model.)