[BenLurkin]

How about this.

Find out which function most impresses which one of the locals and sell the IPhone to that person. Charge a fortune for it.

Don’t forget to skip town right away.

[zeugma]

Actually, an iPhone is not what I'd sell them. There are any number of things that would work better. How about a straight up mechanical automatic watch. No batteries required, but it also doesn't need to be wound, and would keep better time than anything that existed in that time period. I suspect you could make a fortune selling just the escapement to a jeweler.

The best way to make money in the past though, is even easier than that. Simply take ten pounds of aluminum ingots, and trade it to someone who deals in commodities straight up weight for weight for gold. They'd think they were getting a heck of a deal, and thus could be trusted to keep their mouth shut, and you'd be somewhat better off as well. Until the advent of electricity so separate aluminum from ore, it was insanely expensive stuff, and like gold, has the advantage of not being subject to tarnish.