In USA, I believe tobacco is prohibited on institutional ground on a state to state basis. My state doesn't allow tobacco since the 90s. Some states sell tobacco on the comissary.
So in my experience, depending on the facility, most likely if you're in county jail you have to use the mail as there is no leaving the grounds or contact visits - you must soak paper with your desired solution and write a little note on it. This worked very well for synthetic noids. I hear it worked for crystal also, I've heard mixed results about suboxone. Not positive about anything else as everything that comes in is scrutinized heavily, they get x-rayed, dogs etc.
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Another option is contact visits - this is mostly for state prison rather than county jail. Suboxone strips are the main commodity - people make more money coming out of prison than they were making hustling on the streets. People would roll the strips up in plastic wrap and make a little bundle, usually a woman would sneak it in and find a way to get it to you without anyone noticing. Visitors got searched lightly on the way in. You gotta either swallow it, if it will pass without being destroyed, or hide it very well because you will be strip searched after the visit. At $100-200 for a 8mg strip... you could make a small fortune in a short time. Usually you would have someone send a money order to their people and if it worked out you would get your strip. You could break the strip into 16 or 32 pieces and put it in a few drops of water on a spoon and sniff each piece and you'd be up all night cleaning your cell with a toothbrush. Contact visits you could get anything in, but it was usually weed or synthetic noids as incense and suboxone strips.
If you manage to make it to lower security, you might be able to get work on a outside crew picking trash on the highway, or the grounds - people mostly do this just to rummage cigarette butts for tobacco, once in a while something would come through. People might be able to throw something over the fence but that is rather risky and difficult. There are other privileges like work release where you get dropped off and picked up at a local business the facility has contracts with, this is your best bet but takes time to get that position, usually after your first year locked up. I've worked at the state police horse barn shoveling shit, basically everyone had something going on there, there wasn't a bathroom so everyone had to shit in the woods - it wasn't a problem. You could easily arrange a dead drop and most people did. If you can get off the instutution grounds and find a minute or two to yourself and you could get someone to bring you whatever you wanted, if you had that connection, you could sneak a howitzer back inside piece by piece if you wanted - every situation is different so you have to work out the nuances. As long as you boofed it and kept quiet and noone snitched you could do anything. Just make sure to pass your urine screens - most guards didn't even watch you so it's not too difficult.
The last option is if you have a connection on the inside - if a guard is a friend of the family, maybe one of the nurses. Or if you have a really cool attorney. This is rare and difficult and usually didn't last too long for one reason or another, not sure why.