So, this is a pretty heated debate :)
As someone kinda correctly identified, here is what happens:
Agencies are either directed by congress to make certain regulations, or more broadly delegated rulemaking authority.
They exercise that rulemaking authority through an administrative rulemaking and publishing process that ends up with stuff in the CFR.
This part is simple. You can find a parallel table GPO/etc conveniently publishes, of which USC code gave rulemaking authority for which CFR parts here: https://www.gpo.gov/help/parallel_table.pdf
I honestly feel bad for the person who has to keep that up to date.
Now, the larger question that was asked - can you be sentenced to jail for violating a CFR. The answer is "yes". You will likely be charged with some USC violation, whose regulations/etc are interpreted through some CFR regulations.
a good example of a law that has criminal penalties and CFR regulations is HIPAA. See the aptly titled "who goes to jail" - http://www.ehcca.com/presentations/HIPAA3/malone_2.pdf
Notice the regulations are in the CFR, violations of them are explicitly punishable under USC (IE "knowingly and in violation of the regulation ...."). With criminal penalties.
Now, this is not the same as the related question of "can you be sentenced to jail by the FCC for violating the CFR. The answer to this is "well, maybe".
The courts these agencies set up, and their administrative law judges, tribunals, whatever, are generally known as article I courts.
The current state of the law on article I courts is kind of a mess. In general, they have some power, but if it involves deprivation of life liberty or property, it must at a minimum meet various requirements (including being reviewable by a standard article III court).
Honestly, this is a super-complex and super-esoteric topic to get into on hacker news.
So yeah, you should worry about the CFR, but you maybe shouldn't worry the FCC will throw you in jail. It'll be federal prosecutors instead :)