Now, let's be really clear up front, I don't mean getting a surgically implanted chip in your head, done on your kitchen table. Brain hacks are generally either, forming habits that are good for learning and concentration, changing how you do things to help enhance your brains function, eating differently in support of brain health, and, the hard, but easy, but hard, get enough sleep.
Personally, I do quite a few things to try to make this old noodle function better. For example, I carry a Field Notes notebook everywhere. Why? Because the act of writing engages portions of the brain that actually help to remember things. I write things down, so I'll have them later, but writing them down helps me remember them too. That's a brain hack.
Another one I've taken on involves technology ('cause of course it does). I've picked up a smart watch. I'm using it to track my activity on a daily basis. See, I do work out regularly (see my Chores editorial earlier this week), but other than my workouts, I can be a pretty sedentary person. But, in order to improve my heart health and my weight, I'm trying to be more active, walk more, move more, stretch, do stuff. Doesn't sound like a brain hack until you realize that enhanced blood flow to your body, also enhances blood flow to your brain, making it a more finely tuned machine. That is also a brain hack.
There are a bunch of others. Mindfulness and a positive outlook (yes, not always easily attained). Supplements (ooh, careful on this one). Dark chocolate (limited amounts). Fermented food for better gut health (direct links to mood and cognition). Mind mapping (never even tried this one). Pomodoro technique (I can't maintain it, but I'm going to be trying it again soon). Others.
In short, we can do things that make our brains work better. If you don't do any of these, the one I most recommend, get enough rest. Sleep is huge. However, I'd strongly suggest you try some of these out. Or, what are you doing to hack your own brain? Is there a must that I'm missing?