Border Collie? As I've said before on this site, a border collie is not a dog, it's a very bright child in a dog costume ! Best thing to do is give him a set of house keys, the town map, and a 'What's On' guide and let him out for the day to find his own entertainment.
Failing that, he might (with luck), settle without mischief if you start with short absences and gradually build up the time away, just in case, he does this out of frustration or loneliness or anxiety.
The breed is exceptionally intelligent and requires a lot of mental stimulation and interesting exercise and he may well prefer to invent his own games rather than chew a kong or play with any toys you leave him, but that's not say you shouldn't try doing that. That's the ..er..fun of having one. At least he's small. My Irish wolfhounds, bored, once ate a three piece suite and pulled down all the curtains off the rails in the drawing room, and were found sitting happily surrounded by kapok!