No, you have to steal the orb, which ends invisibility
They are in combat, to search something you have to spend at least a Move Action to locate it before using Take Something Unnoticed assuming it's visible to you, because if not, you have to search the target looking for it (similar to looking for a hidden/secret door), which requires at least a Touch attack if your target is mid-combat.
Trying to take something during combat would require a Steal Maneuver, assuming the item is visible and not hidden too, with a bonus from being invisible (+2) and a penalty on the target's CMD as they are unaware of you (losing Dex bonus to AC/CMD), which would then break the spell, being an attack against CMD.
Enemies are not stationary in combat, they are moving, dodging, jumping and swinging their weapons, and you are attempting to search through their pockets for an orb, while they are doing all that and you can't even tell the location of this orb by sight.
Even the Steal maneuver isn't enough to take something that is inside a bag or or backpack. There is a feat for that: Graceful Steal.
You can steal items with the steal combat maneuver even if they are hidden in a bag or pack (provided you can reach the item within), but the opponent gains at least a +5 bonus to its CMD (as for a fastened object) in this case.
Similarly, the Swipe and Stash feat says that you must use the Steal maneuver when trying to use the feat to plant an item on an enemy in combat, instead of a simple Sleight of Hand check against Perception. Though this text is exclusive to the feat, the same logic can be applied to take something unnoticed.
In combat, you must succeed at a steal combat maneuver in order to plant an item on a creature while attempting a Sleight of Hand check opposed by the target’s Perception check to do so without the target noticing.
What you have to keep in mind that, even though you are not attacking or defending yourself, you are in combat as well, you have to roll initiative as soon as your targets and the orcs do, and you gotta act on your initiative order, regardless if they are aware of your presence or not.
Weren't your targets in combat, as the GM, I would allow you to make multiple checks looking for it, depending on how many pockets those enemies got, and depending on whether or not your information about said orb being really inside their robe pockets is correct, as it could be hidden inside a belt pocket, or even in their backpack inside a small chest, etc.
On each of those checks, you first would have to succeed at a Stealth check, to search for things unnoticed, and a Perception check, to use your hands to find it. On each Stealth check, the enemies would be allowed an opposed Perception check to notice your hands shuffling through their things and body. Your own Perception check wouldn't have a high DC, as you know exactly what you are looking for (again, unless your information was false).
This wouldn't break invisibility, as you are not causing harm to your targets in any way.
To be honest, you are probably better first using Detect Magic (since its a magic orb) to find this orb, or waiting for each enemy to be taken down during combat and then search his body, as their enemies (the orcs) won't simply stop mid-combat to search them for the orbs while there is a risk of getting attacked by her enemies.