Small device that i can use to mark times?

I have gotten a new private security contract recently and part of my duties is to make patrols to specific spots at randomized times of the day. I'm supposed to log these times and which site I patrolled.

problem is I tend to be very busy during these patrols managing the guards posted there so i have very little time to stop and write down the time/site and i often forget to do so before moving on to the next one. After a few hours of this I have a LOT of holes in my paperwork.

I was wondering if anyone knows of a device or moblie app (ios for me) that allows me to quickly log times

like an example of what i'm looking for is this:
you can create A B and C on the menu and name them what you want. When you tap A it logs the current time and letter eg.
14:35- A
14:47- B
15:00- C
etc,

at my previous job i simply set alarms throughout the day on my iphone. When it went off, i would go.
I can't do that at this job since the client wants patrols randomized

I know anyone in security, law enforcement, nursing, etc that needs to log times and places during the day would find this useful.
I know i would.

anyone know of anything like this?
it doesn't matter what the intended function is (ie fitness app, cooking, etc.) as long as it suits my needs stated above

14:35- A
14:47- B
15:00- C
etc,

There's a device called a pencil, when paired with a piece of paper would allow you to write down this info, just a fast as using an app. Google it. Oh and there's a thing called a watch that you could consult for the time.