How to tell....if it's not listed in the specifications, my guess would be it doesn't have it. You might want to check with the individual laptop manufacturers.
After looking up what an "accelerometer" is and what it does...I don't know of any laptops that have that built into them. After doing some googling, I see that there are some mentions of HP laptops that have the accelerometer built into them.
What is the name of the sensor? Both the 11s and the 3 11 have a Sensor entry in Device Manager. Both have three sensors listed, HID Sensor Collection, Light Sensor and Simple Device Orientation Sensor. But, the 3 11 seems to be missing something else. If I disable either Hid Sensor.. or Simple Device.. on the 11s, the controls for the F18 game go wonky, but there is still something that works as a control.
I finally talked to a Lenovo tech who had knowledge of the Yoga 3 11. He said that the Yoga was more of a laptop than a tablet and that a position sensor (Accelerometer) was not included in the design! Hey Lenovo, quit advertising a tablet mode if it doesn't have tablet capabilities.