property pre does not exist on schema in mongoose - node.js

Question

I am trying to detect changes in the document via pre hook but it typescript is giving me error that this property does not exist.
following Structured style, not OOP
// category.schema.ts
const categorySchema = new Schema({
category_id: { type: Number, required: true, unique: true },
name: { type: String, required: true, unique: true },
icon_url: { type: String, required: true },
items_quantity: { type: Number, required: true },
items: [
item_id: { type: Number, required: true, unique: true },
item_name: { type: String, required: true }
]
})
const Category: Model<Category> = model<Category>('Category', categorySchema);
export default Category;
Now I want to check for document changes on deletion of subdocument.
import CategorySchema from "../schemas/category.schema"; // schema path
router.delete('/:category/:item', async (req, res) => { // removes an item
let itemsQuantity: number;
let category = await CategorySchema.findOneAndUpdate(
{ category_id: req.params.category },
{ $pull: { items: { item_id: req.params.item } } },
{ new: true });
// pre does not exist
CategorySchema.pre('save', function(next) {
if(category.isModified()) {
log('changed');
} else {
log('not changed')
}
})
const data = await category.save();
res.status(200).send(req.params.item);
})
How to get or enable this hook, any suggestions?