As a Thief, use a scroll via Use Magic Device
Use Magic Device allows a (13th-level or higher) Thief Rogue to use magical items regardless of class, level, or race restrictions. Considering that a spell scroll is defined as being unintelligible if it's not on your class list, a Thief should technically be able to use it.
Now, casting the spell from it is a little harder, as it requires an "ability check with [their] spellcasting ability", with a DC equaling 10 + the spell's level. Per DMG p. 141, a thief rogue's spellcasting ability modifier is +0, so it would simply be a d20 roll with no modifiers; to use a magic jar spell scroll, that's a DC 16 check with no bonuses (a 25% chance of success).
Considering a Thief has no magical talents, that's still pretty cool.
For more info about using spell scrolls as a Thief Rogue, see this question.