Well when it comes to capturing NPCs, very few of them of them actually have the class abilities of PC wizards. Volo's guide breaks it a bit, but even there the specialist wizard options have one arcane tradition ability and from them only the conjurer one is the only really problematic one. So in most cases it doesn't really come up.
In cases you have to worry about stuff... well manacles, a decent gag and a blindfold can do the trick. A creative use of a glyph of warding can be a bonus.
Now when talking about the world in general, the world doesn't need to be built to be built to PC specific. Larger cities or castels can have cells that have been specially built to dampen spellcaster's abilities, at least the more problematic of them
Hmm... i also got a few sudden and pretty rough ideas. 5e doesn't have assumed magical items but in an Eberron-like campaign or if the party is mostly about capturing spellscasters (or one of them is captured by some rich and well-prepared enemy):
Manacles of arcane binding
uncommon? wondrous item
This item dampens the wearers ability to use spells or other abilities of magical origin. When the wearer attempts to cast a spell or use a magical ability, he must succeed a DC 15 constitution(?) save or the spell or ability fails. If the spell is 6th level or higher the spell the check is made with an advantage. in addition while wearing these manacles all saving throws to maintain concentration are are made with a disadvantage.
Special: Some versions of these manacles also emit a loud sound when a successful spell is cast.
Rare version of previous item
The saving throw to cast a spell or ability that causes the wearer to transform, disguise itself, become invisible, teleport or gain any other benefits in mobility, is made with a disadvantage.
Manacles of Magical Backlash
rare+ wondorous item
When worn these manacles have the ability to turn a persons magical abilities back at him. Whenever the person attempts to use a spell or an ability of magical origin, he must make a DC constitution save. On fail the spell or ability is disrupted and the wearer takes 3d8 force damage. If the spell was cast using 2nd level or higher spell, the damage increases by 1d8 for spell slot used. On a save the wearer takes half damage and the ability or spell works as normal.
Special: Some versions of these manacles also emit a loud signal when the wearer successfully casts a spell.
Both of those items are created with the idea of not causing a hard shutdown of character's abilities, but still make it harder to use them.