With Marsden I have to proof outlets, cabinets, close doors to rooms I don't want him to go into (even have to proof em in case he gets in there!), and same goes for the lower objects. Objects not just at "ferret" level, but also at baby level: the coffee table, DVDs, CDs, and other items at ground level. I've even had to move the altar up out of reach, though if he's observant, and we're not, he can use the window sill, the laptop table, or one of us to get there. With the coffee table, he can use the dog as a step or one of us as a bridge.
What Marsden doesn't steal and hide in the back room, he knocks off just for the hell of it. A digger he is! A curious digger at that! Likes to dig behind the DVDs, CDs, and Books (though I broke him of that!), just to see what's behind it. And he's determined! A simple no doesn't work with him. And pulling him away only makes him more determined to get to it and make a mess. Either we have to distract him, OR put him back in his cage. He's even tried to steal DVD's!
I've been trained to listen when he's not in the same room as us. If he makes an odd noise, I get up to investigate.
Ferrets are smart! They learn and they're resourceful. Babies learn too. Perhaps not as quick as a ferret, but still.
Now granted a ferret, or at least Marsden isn't going to explore his world with his mouth like a baby, but I think they're both just as destructive.
Hm, from what I've seen of infant and toddler behavior, yeah, I see a lot of similarities between them and ferrets! So while they may think I'm bullshitting, I've got a feeling that I'm more prepared for a moving infant than they were. Even just a little bit.