Is there a lidar unit I can take home and scan my house at high resolution (than iphone)?

You can, they are just expensive (other than iphone). Maybe 8k for a handheld basic one (e.g. Trion P1), $15k for a drone attachment (e.g. DJI Zenmuse L1) - more for the ones surveyors use proper including the tripod-mount ones.

At the consumer end photogrammetry tends to just be so much cheaper that its preferred unless you really need defined accuracy at a high level of detail. Lidar tends to work currently much better in an industrial/professional context because its more accurate. Whether Lidar will make the jump to lower cost / consumer level is the big open question (and basically the same issue as for cars here)

I was wondering this too, although for a different use-case. A couple years ago I was walking through a field/vacant lot not far from Centralia, WA and I came across what I think is a grave.

The (supposed) "grave" was roughly human-sized and human-shaped, the ground was concave, sunken in and deepest at the center, and it was encircled with stones that were slightly larger than grapefruit.

The reason I suspect it's a grave is because I stumbled upon a very similar-looking thing at a historical site in Tooele county Utah named Mercur cemetery.

With Lidar I could prove/disprove my grave theory, correct?

I think this depends on your budget and what exactly you want to do. Do you want to scan your house from outside? Sounds expensive, would probably have to be drone-mounted, and the drone would fly around for a while (depending on the shape of the house.) Inside, and don't mind some minor inaccuracies? Not Lidar, but a Kinect from yesteryear may be enough.

Lookup the RPLidar family of devices. Cheap 1D, easy to work with. By 1D I mean that it measures ranges in 360degrees around the plane that it is spinning in.