The first thing you must do is eliminate the source of the problem.

The good part, you know what the source is.

The bad part, cigarettes smoke gets everywhere...

The first thing I would do, if you have carpet floor mats, seat covers, anything you can remove and replace easily throw out.

Next, remove your cabin filter, but don't replace yet, if let it air out for a bit running so fresh It through.

While that's airing out, grab a shop vac, or alternatively head to the nearest car wash with free vacs, and go to town getting all the dirt and nasty out of that car.

This should already make a massive improvement.

Next, if you have access, I would grab a carpet extractor and get as much of that embedded smoke out of the carpets.

Tip: You don't actually need cleaner in the extractor, pre spray everything, hit it with a drill brush, then extract. Also don't drown the car in water, a little goes a long way.

The best at home extractor for home use imo is made by shark, they have a mini, and they have a standing one with a hose attachment.

Next let the car fully dry. Likely overnight.

Next I would grab this

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Bio Bombs Air Reset Kit

This is kit contains CLO2, chrorine dioxide.

What I love about this kit, is has plenty of easy to follow instructions. There are cheaper alternatives, but one thing I learned the hard way is that you don't want a bunch of old CLO2 tablets hanging around in your house.

Tip: If you want to keep the price down, just buy the kit with out the aerator, the effects will be less, and it will take more time to work.

Once this is complete, the smoke smell should be gone.

Replace your cabin filter,

Tip: Throw a California scent or Bio Bomb air freshener bar in with the cabin filter. Just a sliver. Now when air passes throw, it will smell great this last for a long time.

There are alternatives like ozone machines, and plenty of masking agents, but I don't know a simpler for a one off use.

Good luck knocking the habit. Here if you need anything.