Taking your child with you to your workplace might seem like an ideal solution, but unfortunately it is not really allowed. Only employees are allowed to come to the workplace, and it might sometimes disturb your work and your colleagues. You need to ask permission to your boss. If he doesn’t allow it, you will have to find another solution. But you can sometimes try to suggest doing teleworking if you work allows you to execute your tasks from home.
https://www.jobat.be/fr/articles/venir-avec-votre-enfant-au-bureau-est-ce-autorise/