Finely chop the celery, scallions, dill pickles, bell pepper. Chop the fresh dill if needed. Mince or press the garlic.
Drain and rinse the chickpeas. In a large bowl, mash the chickpeas with a potato masher until there are no more whole chickpeas.
Stir the chopped vegetables, dill, garlic, mayonnaise, yellow mustard, lemon juice, salt, and black pepper until well-combined.
Combine the vegetable mixture with the chickpeas.