Some people don't want the long farming process. Which I tried to do. But found it tiresome. For some who wonder. EVERYONE KNOWS HOW TO SCAVENGE AROUND FOR ITEMS. but... I'm about to show you the easiest to hardest locations that I've found. To get extreme amounts of items. 100-700 caps per run (takes about 30 min.) depending on how much you can carry.

-so make sure you have at least 120-180 lbs of free inventory. And have a companion like dogmeat who has empty inventory. Best especially if you have lone wanderer perk that gives you more space in your inventory.

-Locations outside of Of Goodnieghbor is a good place to start, as you run into mirelurks, supermutants, Raiders and one or two gunners. (randomly sometimes get 1 or 2 legendaries there.) Best if your level is over 20 and Guns do about 20-30 damage should be fine. REMEMBER TO CARRY AT LEAST 2 STIMPACKS. If you clear the area. Should be able to make 200-500 caps alone off of items.

-Gunners Plaza
Legendary Outside. Many gunners with combat armor, heavy hitting turrets. So make sure you are well prepared and have as much inventory space as you can. Once the area is cleared. MAKE SURE TO HAVE AT LEAST 4 STIMPACKS. HOPEFULLY LEVEL 30+ DONT GO AT A LOW LEVEL. VERY RISKY. Profit upto 2000 caps

-Jamaica Plains
If you are sided with BOS and help the doc get Variable Blood you can get alot of variable blood and few items. The variable blood collect can go anywhere from 5-20 blood variables that the doc buys for 50 caps each. So I think. But you can end up with 300-650 cap profit.

-Roaming for technical documents for quinnlan
Same thing as Blood Variables but technical documents cost less. But you find more expecially in buildings and townhouses. Also will run into Raiders, gunners and animals. Profit runs about 300-1000