How? Work with them. Pay them enough as they don't have to think about it.
Objective metrics are good if you think you can measure accurately for all individuals at the macro level. You may not need that (I mean, really _need_ it for your business to function, unless you're in the metric-tracking business).
If your teams have distinct and articulate enough outputs, you can retribute each team according to its specific outputs. At the macro level, you don't need to have more details (but you still may ask).
Let the team manage its own distribution of the retribution - and so on (so you do need trained managers to do it appropriately at each level).
Objective metrics are good if you think you can measure accurately for all individuals at the macro level. You may not need that (I mean, really _need_ it for your business to function, unless you're in the metric-tracking business).
If your teams have distinct and articulate enough outputs, you can retribute each team according to its specific outputs. At the macro level, you don't need to have more details (but you still may ask).
Let the team manage its own distribution of the retribution - and so on (so you do need trained managers to do it appropriately at each level).