Yes there is . That inexpensive moisture meter that goes for about 15 bucks on Amazon. It’s analog. It will get you in the ballpark. Then you have to start looking at your leaves. I’m a new grower it is a helpful tool.
@Captspaulding 
aye, so there are phone apps, and then there is the classics. A 3 way dampness/ph/light output probe is definitely my go to for laying out my lights. I tried the apps and stuff, way more of a pain in the ass than it should be. The 3 way meters have a ppfd scale that ranges from 1-2000. Now I have a tendency like
@ArtfulCodger to set all of my equipment to waaaay lower output than any light par map, or instructions dictate. It’s never about adjusting your plant to the light, it should always be the other way around. The amount of light amount any particular strain can endure is most definitely subjective to lineage and genesis locations. Always start with everything set low output, high height above canopy. I veg at 40% output at 30-36 inches above canopy. That’s a decent happy medium for most strains in veg. But it’s not set in stone. There will always be an Output% up or down factor to consider depending on what you are running. Throw out manufacturers specs, and start here. It’s always easier to give a plant more of what it needs, as opposed to giving it too much of things and having to correct that. You dig?
Long story short. Less is more, and that 3 way meter will assist you in laying out your lights height and space inbetween lights. If they are in close proximity and the lights foot print washes out in to another lights footprint, they will keep a nice ppfd in zones between the lights as well. Then start to adjust the lights down, or up and always taking note of different height ppfd in conjunction to your grow space and canopy. The other 2 functions of the three way meter, are useless, but to measure light output? Solid gold imo. Holler at a clown if you need anything!
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