Yes. Broccoli and Cucumber have a documented companion-planting benefit. West Virginia University Extension lists broccoli as a companion for cucumber.
This is a practical yes, not a magic guarantee. Keep the normal spacing for Broccoli and Cucumber, watch airflow and watering, and treat the companion note as one useful planning signal alongside sunlight, soil, and harvest timing.
Source basis: West Virginia University Extension companion planting chart. The page does not add extra pest-control or yield claims beyond the sourced fact row.
Spacing tip: Leave vine crops room to run, or use a trellis so the companion is not shaded or smothered.