One of my players learned the Animate Dead spell.
He asked me if he could equip his zombies and skeletons with weapons (Which is possible) or wands.
I'm pretty sure that undead can't use any magic item that requires attunement as there is no mentioning of skeletons/zombies being able to attune to magic items, but I'm not sure wether they can use wands or other magic items that don't require attunement.
In the description of the skeleton in the MM it states
Obedient Servants …
A skeleton can fight with weapons and wear armor,
can load and fire a catapult or trebuchet, scale a siege
ladder, form a shield wall, or dump boiling oil. However,
it must receive careful instructions explaining how such
tasks are accomplished. …
The description of the zombie states:
Mindless Soldiers …
A zombie armed
with a weapon uses it, but the zombie won't retrieve a
dropped weapon or other tool until told to do so.
Based on this I'd deduce that those undead can only fight using weapons and not magic wands.
On the other hand I didn't find anything that explicitly states that it's not possible.
Is there any other source that explicitly states that it's possible/not possible
Yes, creatures created by Animate Dead can use wands and other magic items.
The rules regarding Zombies and Skeletons don't say that they can't be instructed to use magic items. They also don't say they can't attune to items, so we have to revert to the general rules on attunement.
A magic item’s description explains how the item works. General rules on using magic items are deliberately scant in 5th edition, deferring to the specific rules for each item. But in general unless otherwise specified, any creature can use a magic item.
For example the Wand of Magic Missiles just requires a creature to hold it and use an action. Zombies and Skeletons can accomplish this since they are creatures, they can hold objects, and they can take actions.
This includes items that require attunement. The rules on attunement in the Dungeon Master's Guide specify the requirements for attuning to magic items:
Zombies and Skeletons are creatures and can take short rests, so they can attune to magic items unless the description of the item says they can't.
Of course, neither of these creature types can use magic items that have a command word, since the description of both the Zombie and the Skeleton says that they "can't speak".