The Delhi Metro is the cleanest way into and across the eastern side of Gurgaon. The Rapid Metro loop is useful for Cyber City, Sikanderpur, and nearby office districts, but many sights still need an auto-rickshaw or app cab for the last stretch.
Do not assume short distances are walkable. Pavements disappear, crossings can be hostile, and summer heat is fierce. For Sultanpur or Farrukhnagar, hire a car or arrange a taxi for the round trip.