How and where? I spend 4 days reconfigurating the UIS cause of Update. I rather NOT Update again.I actually haven't thought too much about playing Audio at those points, so let me know if any of the advice below isn't enough, I'll try to look into those things for the next update.
For dropping the item to equipment slot or inventory slot you could play a sound using a custom drop action. Multiple drop actions can be used at the same time.
For crafting you could either create a custom Crafting Menu, or perhaps simply add an OnClick listener on the button. If you make a custom CraftingMenu you can override the "OnCraftCompletefunction" from CraftingMenuBase.
Let me know if some of these aren't enough to achieve what you want, I'll try to implement something easier in the next big update when our new Audio System comes out with UCC and UIS.
[Serializable]
public class BoolUnityEvent : UnityEvent<bool> { }
[Tooltip("An Event called when the crafting is done.")]
[SerializeField] protected BoolUnityEvent m_OnCraftComplete;
/// <summary>
/// When the Craft has been complete send an event.
/// </summary>
/// <param name="result">The crafting Result.</param>
/// <param name="selectedRecipe">The selected Recipe.</param>
/// <param name="inventory">The Inventory where the item was added.</param>
/// <param name="quantity">The quantity crafted.</param>
public virtual void OnCraftComplete(CraftingResult result, CraftingRecipe selectedRecipe, Inventory inventory, int quantity)
{
m_OnCraftComplete.Invoke(result.Success);
}