We highly recommend against it!
Conditioners almost always have a creamy texture, this type of cream can easily accumulate and build up inside your dreadlocks.
Conditioners are also partially designed to be a lubricant to prevent knots from forming. Dreadlocks are essentially knots of hair. Therefore, using a conditioner is counterproductive to forming dreadlocks.
If your hair and scalp is unreasonably dry you can try pure aloe gel, coconut oil, or a dreadlock moisturizer that will all be better than a typical conditioner.