I have experience with the larva of the carpet beetles for 2 years in the place I live now, and never to infestation, never to the hatching, the thing that worked for me is sprinkling Diatomaceous Earth (From amazon) around all the skirting boards and furniture, leaving it in a faint cover, vacuum it if there's too much in mounds, it comes in pale brown or white, mostly does not smell and if it does the smell goes. If you wear a mask and glasses when you do it, that may help if you're concerned about breathing the fine powdery airborne stuff in, but it's safe, food grade, and have used it zero issues for years. any larvae or pupae have to move through it, it dries their exoskeleton out, they show up dead. We find a few here and there, at various skirting boards, so assuming the creeps are creeping about there.
I know it's scary but I promise (From someone with high anxiety) seeing them is not going to lead to infestation, you can stop them with regular vacuum, vigilance, and remember so many people, including me have defeated them, and they go, even if they come back, they go away again. it's seemingly part of being here, some houses have more or some, some do not.
The first step other than vacuum, the D.Earth is banishing fear where possible, that you will and can prevail at this. If someone (me ,others) can, you can. I did it with no toxins, and keep a back up of Indorex spray (used once for fleas in another house) in, in case. Then go full on nuke with house empty for 2-3 hours, I know someone who ended them with that but I never had to.
I echo other posts here, a few, even 10+ every now and again in various rooms, please do not be afraid, it does not mean infestation. Pest control people also say it, they'd not even treat that as an infestation, they are common in UK houses, landing in April may, sometimes crawling about in Aug - nov, before hibernation, hatching circa April may if they even do. They will die by then, am sending anyone who reads this super turbo charged quantum manifestation: removal of the beetles ! x