Superannuation that is split from one spouse to another is no different from any other superannuation. It cannot be accessed unless you satisfy a condition of release (usually retirement) or can prove financial hardship. However, only a limited amount of superannuation can be withdrawn under financial hardship and can result in significant tax being taken from the payment.
The except to this is the superannuation withdrawl permitted as part of the COVID-19 Coronavirus government package.