As a man, you might carry things in your pockets like a snuff box, handkerchief, keys, money, misers purse for coins (though that often hangs out), and also keep a variety of small items on what was termed an equipage (today we use the term chatelaine). On that you'd have watch and watch key, a seal, and lots of other dangle bits much like a charm bracelet today.

Women have generally the same sorts of things, though our pockets hang from the waist under the petticoats. Ever heard the rhyme Lucy Locket lost her pocket, but Kitty Fisher found it- Not a penny was there in it, only ribbon round it? Sewing implements are sometimes on an equipage or carried in a small kit or housewife. Women less often carried watches then men and they're much harder to find today (smaller size). Though those could hang from an equipage, chain, or ribbon. Pinballs are probably far more common and hang the same way from the apron waist or petticoat. Womens clothing was most often fastened with pins, so it kept them at ready hand.

Careful with "modern reproductions". There are many incorrect ones out there inspired by, but not accurate. Watches were sometimes actually two pieces, not just the portion we are accustomed to seeing today, but a shell with open front that fastens over it. Some of the more unusual ones were even shaped like skulls!

Since you made the mistake of saying "person" and not "man..."

18th century women's dresses did not have pockets as we think of them, they had essentially cloth purses tied under their petticoats, with slits through the dress for access. A lady would most likely carry a hanky, and she might carry money, her sewing things, a small prayer book, or a snuffbox if she does snuff. She would probably not put her watch in her pocket, if she had a watch, women primarily wore pendant watches. Modern recreation for sale. She might be carrying a muff it it is cold. V&A Museum has a nice overview.