I was looking at this article.
It recommends allow the usage of dtrace without root for current user, so I run:
$ sudo chmod u+s /usr/sbin/dtrace
Password: # I enter in my password
chmod: Unable to change file mode on /usr/sbin/dtrace: Operation not permitted
Does anyone know if I should, and how I should, allow dtrace to run without root permissions?
I'm not sure what article you were reading, but its advice is unsafe and incorrect. You should never change permissions on files stored in system locations, like /usr/bin and /usr/sbin. (Indeed, System Integrity Protection makes this impossible.)
If you need to use dtrace, run it using sudo.