Connect Apple Thunderbolt to Lenovo T420s
The cables in the top photo are of a MagSafe connector for an Apple laptop, (on the right,) and either a Thunderbolt or Apple DisplayPort connector, (on the left.)

The Lenovo has the standard VGA 15-pin and a DisplayPort (VESA) output which supports a single-link DVI-D 45J7915 cable. It is not compatible unless you can find a VESA DisplayPort to Apple Mini DisplayPort adaptor.

Perhaps the Lenovo 45J7915 cable &lt;> M-M DVI-D cable &lt;> Apple Mini DisplayPort/DVI would work for you. I cannot predict if it will.

YMMV.