I often have to listen to the same part of an audiobook half a dozen times, or more if I'm really stressed. My mind is always racing over something (contributing to insomnia). Sometimes one sentence in a book will trigger a memory and a winding train of thought, and on the next listen, that same sentence will remind me that that's what started my mind wandering in the first place, and so on.

Eventually, I get sucked in and can concentrate for longer periods. Because they force me to listen, I use them for sleeping. Taking my mind away from everything else helps me fall asleep and stay asleep.

I've also found that playing simple games that don't require much thought allows me to concentrate better on the audiobook for some reason. And it tends to be easier in my experience to concentrate on books that are really funny, especially if you're driving.

Edit: tbf my mind also wanders while I'm reading. My eyes will drift across and down the page almost on their own and I will not have read any of it.