When my kids were babies and I would change their diapers I would hand them a toy to play with while I changed their diaper.
The toy was sometimes enough to distract them from wiggling around while changing the diaper.
Other times I would hand them a new diaper to hang onto while I removed their old diaper and put a new diaper on them.
Just don't allow the baby to chew on the diaper like my baby tried to do once.
If you can have the babies dad or mom etc or someone distract the baby by playing with him or her which can keep the baby distracted enough to allow you to remove their dirty diaper, clean them up and put the new diaper on.
As the baby gets older they will sometimes start fighting diaper changes and sometimes you'll have to have someone help you hold the toddler down while you change their diapers.