They can jump pretty far, are very good at climbing and likes to explore holes and small spaces. It's normally not hard to keep a ferret in an ordinary home, but you have to think about what they can do and observe what they like to do.
What you should do is to place all house plants out of reach (what that is, you have to find by trial and error), cover small openings (they can squeeze through smaller holes than you might think). You should also beware of furniture they could get stuck in.
Naturally you also have to be very attentive so you don't step or sit on them in case they lie motionless under a blanket or carpet.
The most fun
is to run in tunnels, chase and wrestle other ferrets, steal
and hide things and dig in flowerpots.
Tunnels you can arrange with plastic tubes, soil
to dig in is also easy to furnish them with, with only a
small risk of untidyness: Put buckets with soil inside a
larger box, it works for us.
Ferrets may be smart in many ways, but they have no sense at all when it comes to not eating dangerous things, like parts of rubber toys, ear plugs, pieces of string and many more things. If you cannot keep such things under strict control you shouldn't have ferrets.