A high pitch squeal from the engine bay area could be one of the following, check through each one:

Alternator belt is slipping

Check alternator belt is tight.

If loose, tighten alternator belt.

Check belt for cracks or damage, if damaged replace. You can purchase replacement alternator belts here.

Excess grease on CVT cone faces

Visually check for excess grease.

If there is excess grease clean with solvent (degreasing/brakeclean).

Check CVT belt for cracking or possible damage, if damaged replace. You can purchase new CVT drive belts here.

CVT belt squealing when coming to a stop

NOTE: there is a normal 'squealing' noise, albeit not as high pitched, that occurs when the CVT disengages the drive belt. 

This only happens when you are coming to stop or heading down hill and is nothing to worry about.

If this noise is excessive, you can reduce it by checking and ensuring the CVT belt tension is correct - this will reduce the amount of noise.

You can also further reduce (even eliminate) this noise altogether by using a high performance CVT drive belt instead of the standard belts. 

They are more expensive and are designed for high performance racing, they are made from a different material and do not rub as much on the CVT face. 

You can purchase one here.