Certified GKH Gardening Expert
If your drumstick tree (Moringa) is less than 2 to 4 years old, it may be too young to produce fruit. It should produce fruit in the next few years. Also, if you harvest leaves from the tree, it may not have enough energy to produce fruit.
Another possibility is that it needs potassium. Adding a potassium-containing fertilizer might help.
MOMAX3 Moringa variety gives first harvest just within 4-6 months of plantation. see here: https://youtu.be/ZziiQ90WMd8
To know Moringa in totality attend 6th Global Moringa Meet 2018:http://jatrophaworld.org/global_moringa_meet_81.html