For my car, I have an anti-theft device call the Club. It is a telescoping device that hooks on each side of the steering wheel and locks in place with a key. Can it be broken? Probably, but the idea is to present a time-consuming obstacle to the thief who relies on speed.
For my MacBook Pro, I have the Blade by Maclocks. The Blade sits inside a bracket that affixes to the bottom of my computer. The Blade folds out from the bracket, providing a slot in which I can attach a lock tethered to a cable.
It is most secure when you loop the cable through an anchored object, like a pole or, in the case of one coffee shop from which I like to work, a table support that is bolted to the floor.