[andrewlowe3]

I'm replacing an old light switch with a Lutron Wifi one. However, the old switch isn't grounded. There is a green wire attached but it is just capped. The new one does have a ground wire. Does that matter ?

 

[daveb1]

Does your new switch require a neutral? If so, is there one tucked into the back of the box?

Switches do not require a ground to work, although some can use the ground in place of a neutral. If there is a ground wire in the box then wire nut it to the ground wire of the switch.

 

[CodeMatters]

Agree with @daveb1 .
Also, last guy made joint poorly. Uninsulated wire should not extend outside
of wire nut.

 

[Missouri Bound]

Does your new switch require a neutral? If so, is there one tucked into the back of the box?

Although it is now code, it wasn't for decades.
It is not uncommon to find only a switch leg in a switch box.
You will be fortunate to find one if you home is older.