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Source: https://lcsc.com/product-detail/Vibration-Motors_Lian-Xin-Technology-XDMD-YB200-08_C47118014.html
Applying current changes the vertical position. You would glue a lens onto this and place it above your camera sensor.
Machine-translated page from the datasheet:
Depending on how its built you might be able to do adjustment and sensing with a single coil. Similar to how you can do current sensing in motors or how you can send and receive with the same coil in a metal detector.
I'm skeptical, but I kind of want one to mess around with. (How fast can it move, how accurate, etc)
I never worked with these before, but these coils are apparently called "Voice Coil Motors" (VCM). The one from this post is big but its the same tech that is used on a smaller scale in phones.
I went and found a "driver" for these things and took a look at the datasheet to understand how a VCM is typically controlled. This thing is 1.5mm x 0.8mm small so something you might actually find in a phone.
The driver chip has built in current sensing and the current going through the coil directly corresponds to lens position so just from that, the driver knows where the lens is positioned.
https://www.ti.com/lit/ds/symlink/drv201.pdf#page=8
Because the lens stack is spring mounted it can lead to "ringing" which basically means bouncing that continues after the desired position was set. So the chip apparently has built in logic for compensating for that so it more smoothly reaches the desired position without overshooting.
The ringing comp is interesting: it's completely synthetic (sensorless). The chip models what it thinks the ringing should be based off some physical parameters (that can be configured over I2C), then drives the coil in a way that it hopes would counteract the ringing, but never actually knows if it has succeeded.