There are many better ways to acquire caps.

Selling:
Purified water
Any cooked meats
Unused meds
Unused mods
Weapons/armor that you have all of the mods unlocked for

Build and sell Marine helmets. They use glass, rubber, and plastic. You get 19 per helm without extra charisma or perks. Extra perks can get you over 30 per item. I wipe out the vendors 1400 stash almost daily.

Build a bunch of water purifiers > wait 10 minutes > sell 1 bottle for 4 caps each

If you mean, the fastest in terms of just getting out of the vault...sure.

Otherwise, all you really need to do is wipe out an easy area like New Gad (tons of mutants that also drop caps) and collect every weapon from the bodies, walk to nearby Station (even over encumbered as its not that far) swap in the Bargain card pop Grape Mentats and sell it all. You'll hit the vendor cap in a couple of runs through any area similar to it.

This is part of my daily routine and earn 1200 caps in less than an hour. I move onto Dailies from there.

Kill mirelurks and equip the perk that gives you a chance for extra meat. One of the 'stop mirelurks from getting to the island event' up north, along with mirelurks naturally there can give you 50+ meat. With the perk you can get up to 3 meat per enemy, that when cooked sells for like 20+ caps total.

Terrible guide.

Or you can just sell all the weapons and Armour Peaces you dont need, you can swap perk cards anytime you want, When at a vendor equip The Hard Bargain card and Party Boy/Girl (Charisma), pop a Berry Mentats and boom, youll have loads a money in no time.

the moth man eggs do they repawn?

sell mothman omlets

Dont spend it all