One of the basic purposes of publicly declaring a marriage is so that no doubts can be raised about the legitimacy of the marriage and the children.
When a marriage is done secretly, it defeats the universal purpose of marriage. Hadrat Khalifatul-Masih IV rta said that the marriages of peoples of all religions and cultures, “are held to be right in Islam according to their customs, if nothing underhand is adopted (Question Answer Session, Aug 9, 1985).”
One’s intentions and efforts should be to announce the nikah publicly. If a nikah is done with the intention of hiding it, then it goes against the teachings of Islam. It is not possible to secretly have a public announcement while remaining true to ourselves.
During the time of the Holy Prophet sas, drums would be used to announce marriages. In Tirmadhi under the chapter, What has been related about publicizing the marriage, it is narrated that the Holy Prophet sas said:
Publicize this marriage, and hold it in the Masjid [Mosque], and beat the Duff [drum] for it.(Sunan at-Tirmadhi, vol. 2, Book 6, Hadith 1089)
However, the custom of making announcements with drums should not lead to dancing and sinful practices. The Promised Messiah as said:
Many times, matters related to marriage get to the point of court cases, and then inheritance is affected, so announcing the marriage is necessary, but the announcement should not have any aspect in it that is a means of wickedness. Entertainment by promiscuous women and fireworks are wickedness and wastefulness; they are not permitted.(Fatawa Hadrat Masih Mau‘udra, p. 170)
Hadrat Musleh Mau‘ud ra said:
The purpose of drums was to announce. Now a means of announcing has come out that is far superior to drums, which is newspapers, wherein announcements can be made. The purpose that drums had has now been fulfilled through other means that are better.(Fatawa Hadrat Musleh Mau‘ud,vol. 2, p. 40)