Question for smokers....

I’m wondering if I could get some help for a story I’m in the planning stages to write.

If there are any Smokers out there, can you explain to me how it “feels” to “Need” a smoke.

In a body swap story, a non-smoker ends up in a smokers body, and not being originally a smoker himself, how would the swapped person know the new new body is craving a cigarette ?

Thanks in Advance.

Sapphire