To secretly watch or gather information about someone.

जासूसी करना

English Usage: She was spying on her neighbors to find out what they were doing.

Hindi Usage: वह अपने पड़ोसियों की जासूसी कर रही थी यह जानने के लिए कि वे क्या कर रहे हैं।

The act of secretly observing or gathering information about someone or something.

जासूसी

English Usage: The spying was conducted under the cover of darkness.

Hindi Usage: जासूसी अंधेरे की ओट में की गई थी.