The following are the only hits I get for John Chapman in 1861 & 1871

1861
RG9/4416, District 2, Folio 124, Page 6,
Household schedule number 450
3 Queen Street, Douglas
Thomas Sayle, Head, M, 40, Carter, Douglas
Hannah, Wife, M, 30, Douglas
Robert, Son, Un, 13, Douglas
Elizabeth, Daur, 9, Douglas
William, Son, 5, Scholar, Douglas
Thomas, Son, 1, Douglas
Henry Quay, Servant, Un, 21, Servant, Malew
John Chapman, Servant, Un, 30, Servant, Douglas
Elizabeth Chapman, Mother in Law, Widow, 79, Invalided, Castletown

1871
RG10/5776, District 2a, Folio 42, Page 19, Household schedule number 115
33 Barrack St, Onchan
John Chapman, Head, Mar, 40, Carter, Douglas
Eliza, Wife, Mar, 35, Douglas
John, Son, 10, Scholar, Douglas
Benjamin, Son, 7, Scholar, Douglas
Thomas, Son, 4, Scholar, Douglas
George, Son, 1, Douglas