Random.insideUnitSphere

Description

Returns a random point inside or on a sphere with radius 1.0 (Read Only).

Note that the probability space includes the surface of the sphere because value, which is inclusive to 1.0, is used to acquire a random radius.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Start()
    {
        // Sets the position to be somewhere inside a sphere
        // with radius 5 and the center at zero.

        transform.position = Random.insideUnitSphere * 5;
    }
}